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UKMT Intermediate Mathematical Challenge, 2024

Algebra Difficulty 2.0 Junior Find the answer United Kingdom

The ages of Grannie's seven grandchildren are consecutive positive integers. The youngest three grandchildren have a mean age of 6. What is the mean age of the oldest three grandchildren?

(A) $8$ (B) $9$ (C) $10$ (D) $11$ (E) $12$

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